1. Field of the Invention
The field of the invention relates to hardware components and, more specifically, an adjustable foot insert for tubing and a method of making such an insert.
2. Description of the Related Art
Adjustable foot inserts widely used in commmercial food service equipment and other situations where it is desirable or required to have legs on tables, components, appliances, etc., that are adjustable. Since it is required by many sanitary codes that devices used to support food service equipment have no exposed threads, an adjustable foot insert was developed which comprises two pieces that are die cast and then assembled. A foot element is die cast in a cylindrical shape, with one end being the bottom and flattened for contact with the floor, and the other end, or top, being threaded. A cylindrical sleeve is then die cast, with a smooth interior. Threads are then tapped or machined onto the interior surface of the sleeve, the foot is threaded into place, and the top portion of the sleeve, opposite the end where the bottom portion of the foot protrudes, is then folded over in a process called swaging. The assembly can then be inserted into the hollow bottom of a leg of the appliance or table to be supported and the height of the appliance can then be adjusted by turning the foot element, thereby lengthening or shortening that leg. These inserts can also be used to compensate for uneven floors and ensure that an appliance or table is level and firmly seated on the floor.
Referring now specifically to the drawings, FIGS. 1-1A show the prior art adjustable foot insert. The prior art adjustable foot insert 52 is manufactured in the following manner. A sleeve element 2 is die cast in a tubular form and has an outside surface 16 and an inside surface 3. After the sleeve 2 is die cast, spiral threads 4 are tapped onto its inside surface 3. This separate tapping process is necessary because threads cannot be easily die cast on the inside of a hollow tube. A foot element 6 is then manufactured according to the prior art, being cylindrical in shape, with a lower end 14 and an upper end 12. The lower end 14 is either round or hexagonal in shape, and is hexagonal in the prior art insert shown in FIGS. 1-1A. The upper end 12 of the foot element 6 is cast with spiral threads 8 on its outside surface. The foot element 6 is then threaded into the upper end 48 of the sleeve element 2, as shown in FIG. 1. The threads 4 that are tapped onto the inside surface 3 of the sleeve element 2 begin at the upper end 48 of the sleeve element 2 and proceed close to, but short of, the lower end 50 of the sleeve element 2. The lower end 14 of the foot element 6 is passed through the upper end 48 of the sleeve element 2 and out of the lower end 50 of the sleeve element 2. The threads 8 of the upper end 12 of the foot element 6 come in contact with the threads 4 of the internal surface 3 of the sleeve element 2, at which point the foot element 6 can be threaded all the way into the sleeve element 2 until the bottom of the threads 8 of the foot element 6 reach the end of the threads 4 in the lower end 50 of the sleeve element 2.
It is important that the foot element 6 be prevented from unscrewing completely from the sleeve element 2 during adjustment of the height of the foot element 6 after installation into the leg of an appliance. Accordingly, after the foot element 6 is threaded into the sleeve element 2, the upper end 48 of the sleeve is rolled over, or swaged, to create a swaged end 18 (FIG. 1A) beyond which the foot element 6 can no longer pass.
The process of making this foot insert is expensive, because the outer sleeve is die cast in one piece. Particularities in the process of die casting make it impractical or impossible to die cast a hollow cylinder with threads on its inside surface, so these threads have to be tapped onto the inside of the tube after it is die cast. Also, it is important to prevent the foot insert from being threaded all the way out of the sleeve in either direction. Preventing the foot from being threaded out of the bottom of the sleeve is done by tapping threads inside of the sleeve close to, but not reaching, the bottom of the sleeve, thus preventing the foot from being lengthened too far. Preventing the foot from being threaded out of the top of the sleeve is more difficult to accomplish. In the known insert, this is done by swaging the upper end of the sleeve after the foot element is threaded into the sleeve, thus preventing the foot from being shortened too far.
The disadvantages to this method of making the insert are that it is time consuming, expensive and inefficient to tap the threads onto the inside of the die cast sleeve, and it is equally disadvantageous to swage the top end of the sleeve after the assembly of the insert.
The method to be disclosed overcomes these disadvantages by eliminating the need for the separate steps of tapping threads and swaging the sleeve, thus allowing a cheaper and more efficient manufacture of the insert.